He said the "violence of ultra-nationalists threatens the lives and the regional interests of Russians and the Russian speaking population".

Mr Lavrov, who will meet UN Secretary General Ban Ki-moon in Geneva later, also condemned Western threats of sanctions and boycotts.

The BBC's Imogen Foulkes, in Geneva, says the comments were in stark contrast to those in a text previously distributed to journalists, in which Mr Lavrov said that "military interventions on the pretext of civilian protection produce the opposite effect".

In Kiev, Ukraine's Prime Minister Arseniy Yatsenyuk said that any attempt to seize Crimea would fail.

However, he also said that "for today, no military options are on the table", urging instead international economic and political support.

The crisis has hit Russian stock markets, with Moscow's main MICEX index dropping 9% in early trading. The rouble fell to a fresh all-time low against the US dollar and Russia's central bank raised its key lending rate to 7% from 5.5%.

The BBC's Mark Lowen in Sevastopol says Crimea is now under de facto Russian armed control although no shots have been fired.

He says two large Ukrainian military bases are surrounded and key installations like airports are occupied.